The Public Service Association is calling on the Government to match the Australian prime minister Julia Gillard's pledge to invest $NZ2.6 billion into closing the pay equity gap.

Gillard last month announced she was prepared to put $A2 billion over six years into wage rises for 150,000 community service workers, 80 per cent of whom are women, saying it was an important step towards closing the pay gap.

The deal would give the workers an average pay rise of $NZ15,800 but still has to be approved by Australia's national workplace relations tribunal, Fairwork Australia.

Gillard said Australian women earned on average a fifth less than men which means they worked ''nearly seven weeks every year for free''.

In New Zealand it is estimated men earn on average 12 per cent more than women.

PSA national secretary Brenda Pilott said National came into office in 2008 after campaigning to close the wage gap with Australia.

''If it's truly committed to that goal it will follow Julia Gillard's example.

''If the new National-led Government were to implement a similar pledge here, not only would it be addressing the pay disparity between men and women, it would also be taking action on the widening gap with our neighbour across the Tasman.''

Nearly a third of government departments had gender pay gaps above 20 percent, she said.

In the Ministry of Defence it was nearly 39 percent.

''These are shameful statistics given that 59 percent of New Zealand's public service workers are women.''

Minister of Women's Affairs Hekia Parata said the Government was committed to reducing the gender pay gap, but had no plans to match Australia's $NZ2.6 billion pledge.

"This is a challenging economic climate and our priorities are to provide better public services to New Zealanders, while reducing debt and building a faster growing economy."

The gender pay gap was currently at 9.6 per, the lowest ever, she said.

The Government had worked hard with the accounting sector to encourage flexible work practices.

It had also set up trade networks in main cities to help women get into male-dominated trades and launched an online tool to help women who want to serve on boards.

The NZX stock exchange was also proposing new rules requiring all publicly listed companies to declare how many women they have in senior roles and the New Zealand Institute of Directors had established a new mentoring scheme aimed at women.

"We are making progress but there is always more that can be done.

"Our Government is committed to growth and we recognise the contribution that women can make to that."

Finance Minister Bill English boasted in April that New Zealand's low wages helped it compete with Australia, Pilott said.

''But this doesn't stand up to scrutiny.

''A recent report from (investment company) Goldman Sachs estimates that closing the pay gap between men and women in New Zealand would boost New Zealand's GDP by 10 percent.''

Gillard's government was showing ''real leadership'' by addressing the issue.

The call comes as the Greens, who have called for action to be taken to close the pay gap, yesterday expressed its disappointment the number of female MPs in Parliament had reduced for the first time since the introduction of MMP in 1996.

MP Catherine Delahunty said National was behind the decrease.

''Over half of our MPs are now female, this is in stark contrast to National whose caucus only has 15 women out of 60 MPs.'' National only had three female MPs in its top 20 which showed it wasn't committed to gender representation, she said.

There are 38 female MPs in this term's intake, down from 41 in the 2008 intake.